Embodiments relate to a negative high voltage generator, and more particularly to a negative high voltage generator that is small in size, and a non-volatile memory device including the negative high voltage generator.
Generally, magnitude of a negative supply voltage is amplified using pumping stages, each of which includes an N-type metal oxide semiconductor (NMOS) transistor formed on a P+ type silicon substrate to generate a negative high voltage. Each of the NMOS transistors included in the pumping stages amplifies a magnitude of a negative voltage received from a previous pumping stage and provides the amplified negative voltage to a next pumping stage.
Usually, when a negative high voltage is applied to an NMOS transistor, leakage current flows from a drain region of the NMOS transistor to a P+ type silicon substrate, so that the NMOS transistor cannot sufficiently amplify the magnitude of the negative high voltage. To prevent the leakage current, a P+ type well surrounding a source region and a drain region of the NMOS transistor, and an N+ type well surrounding the P+ type well is formed in the P+ type silicon substrate in a conventional negative high voltage generator, an example of which is shown in FIG. 11.